[libvirt] Hide fully-virtualized network devices to domU with PV drivers

Iain Watson iain at ij-watson.co.uk
Fri Nov 28 11:03:31 UTC 2008


I have a problem with libvirt which I hope someone on this list might
be able to help with.

I have many DomU images which all have PV drivers loaded for network.
I want to start these DomU guests with only the PV network device
being visible from within the DomU.

In testing I have been able to create the required system with the
'xm' command. The important part of the network line is "type=none".
The complete line looks like:

  vif = [ "mac=00:16:3e:00:a5:57,bridge=eth0,script=vif-bridge,type=none" ]

With libvirt I have tried adding "<model type='none'/>" into the
interface section but this errors with "qemu: Unsupported NIC: none"
so I'm obviously missing something obvious. The complete interface
section looks like:

    <interface type='bridge'>
      <mac address='00:16:3e:00:a5:57'/>
      <source bridge='eth0'/>
      <target dev='vif9.0'/>
      <model type='none'/>

I have been able to achieve the required configuration if I completely
omit an 'interface' section and once the DomU has booted I use virsh
to add an interface to the domain. Unfortunately if I then reboot the
DomU the guest comes back up with two network interfaces visible to it
and the qemu-dm line has added a "-net ...,model=rtl8139" option.

Having hunted around I am yet to find a way to configure a domU in
libvirt so the networking available to the guest is the way I require.
As I can do this with xm, I'm hoping someone on this list can point me
in the right direction to also do this with libvirt.

Thanks in advance,
Iain Watson

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